Japanese Unexamined Patent Application Publication No. 2012-027760 discloses a system that performs lane keeping support and lane departure warning (see paragraph and the abstract). According to Japanese Unexamined Patent Application Publication No. 2012-027760, a lane detection unit 10 detects a lane on the basis of an image taken by an image pickup unit 2 (paragraph [0012] in the publication). A lane keeping support unit 11 calculates a steering angle needed in order to keep the vehicle in the present lane and operates a steering motor 5 via a power steering control unit 6 (paragraph [0012]). A lane departure warning apparatus 12 determines a possibility of the vehicle departing from the lane on the basis of lane information detected by the lane detection unit 10, and produces an alarm to the driver if it is determined that the vehicle is to depart from the lane (paragraph [0012]). According to Japanese Unexamined Patent Application Publication No. 2012-027760, if a curve radius from the navigation apparatus 13 is equal to or less than a pre-set value, the lane departure warning apparatus 12 notifies the driver by voice or the like that the lane keeping support or the lane departure warning will become invalid (paragraph [0013]).
Japanese Patent No. 4654208 discloses a lane departure prevention system or the like that acquires information about the environment around a host vehicle by using a vehicle-mounted camera 3a and supports in the driving of the host vehicle and produces alarms to occupants of the vehicle (paragraph [0010]).
Neither Japanese Unexamined Patent Application Publication No. 2012-027760 nor Japanese Patent No. 4654208 provides any consideration that focuses on the vehicle travel support during a turn along a curve.
Accordingly, the present application describes a vehicle travel support system and a vehicle travel support method capable of more suitably performing the vehicle travel support when the vehicle turns a curve.
A vehicle travel support system according to a first aspect of the disclosure includes an image pickup apparatus that takes a front image of a view ahead of a vehicle, a lane detection apparatus that detects a lane indicated on a travel path of the vehicle from the front image acquired by the image pickup apparatus, a position detection apparatus that detects a present position of the vehicle, a map information storage apparatus that stores map information, an actuator that generates a steering assist force, and a control apparatus that assists in keeping the vehicle in the lane or avoiding departure of the vehicle from the lane by causing the actuator to generate the steering assist force. The control apparatus estimates the travel path of the vehicle based on the present position of the vehicle and the map information, acquires, regarding a curve included in the travel path, a curve radius contained in the map information from the map information storage apparatus, performs at least one of a vehicle turning support and a deceleration support prior to entry to the curve, based on a start point of the curve which is detected based on the front image, and performs the vehicle turning support for the curve by using the curve radius contained in the map information.
According to the first aspect of the disclosure, the vehicle turning support or the deceleration support prior to entry to the curve is performed on the basis of the start point of the curve which is detected on the basis of front images taken by the image pickup apparatus and the vehicle turning support for the curve is performed by using the curve radius contained in the map information. Therefore, it becomes possible to perform a suitable deceleration support or a suitable vehicle turning support with reference to the start point of the curve detected with high accuracy by using front images and perform a highly accurate vehicle turning support for a curve based on the map information.
The control apparatus may start the vehicle turning support for the curve which uses the curve radius, when steering is performed by a driver of the vehicle. Therefore, it becomes possible to perform a vehicle turning support that reflects tastes of the driver. Furthermore, it also becomes possible to prevent a sense of strangeness about the steering assist force from being given to the driver.
In the foregoing vehicle travel support system, the control apparatus may compute a first steering assist force that is the steering assist force that reflects at least one of a target yaw rate and a target lateral acceleration that are based on the curve radius and vehicle speed and also computes a second steering assist force that is the steering assist force that reflects the vehicle speed and at least one of vehicle yaw rate and lateral acceleration, and may start the vehicle turning support based on the first steering assist force, subsequently change the steering assist force gradually or stepwise from the first steering assist force to the second steering assist force, and then perform the vehicle turning support using the second steering assist force. Thus, it is possible to perform a smooth transition from the first steering assist force that reflects the curve radius to the second steering assist force that reflects the vehicle yaw rate.
The control apparatus may cause the steering assist force to be generated by using as a reference a start point of the curve which is detected based on the front image. Thus, even if the driver does not perform steering or the amount of steering performed is small, the steering assist force is generated so that the vehicle can smoothly turn the curve.
The control apparatus, while performing the vehicle turning support for the curve by using the curve radius contained in the map information, may reduce the steering assist force so that the vehicle turning support ends at an end point of the curve which is detected based on the front image. Thus, the vehicle turning support for the curve which uses the radius of the curve contained in the map information can be ended in accordance with the end point of the curve detected on the basis of front images. Therefore, the vehicle turning support can be highly accurately ended.
A vehicle travel support system according to a second aspect of the disclosure includes a position detection apparatus that detects a present position of a vehicle, a map information storage apparatus that stores map information, an actuator that generates a steering assist force, and a control apparatus that assists in keeping the vehicle in a lane or avoiding departure of the vehicle from the lane by causing the actuator to generate the steering assist force. The control apparatus estimates a travel path of the vehicle based on the present position of the vehicle and the map information, acquires, regarding a curve included in the travel path, a curve radius contained in the map information from the map information storage apparatus, performs at least one of a deceleration support and a vehicle turning support based on a current that maintains at least one of a vehicle yaw rate and a lateral acceleration that occur on the vehicle, and performs the vehicle turning support for the curve by using the curve radius contained in the map information.
According to the second aspect of the disclosure, at least one of the vehicle turning support and the deceleration support based on the current that maintains at least one of the lateral acceleration and the vehicle yaw rate is performed and the vehicle turning support for the curve by using the curve radius thereof contained in the map information is performed. Therefore, it becomes possible to perform the vehicle turning support or the deceleration support that maintains the lateral acceleration of the vehicle yaw rate and perform a highly accurate vehicle turning support for a curve based on the map information.
The control apparatus may cause the steering assist force to be generated before the vehicle enters the curve. This makes it possible to notify the driver in advance that the vehicle turning support will be performed for the curve.
The control apparatus may determine a delay of an actual steering timing at which steering is performed by a driver of the vehicle from a reference steering timing that is a steering timing set with reference to a start point of the curve and may advance a start timing of starting the steering assist force prior to entry to the curve, according to the delay of the actual steering timing. Therefore, the timing of starting the steering assist force prior to entry to the curve can be adjusted according to the skill of the driver.
In the foregoing vehicle travel support system, if the vehicle has passed a steering-requiring position set with reference to the start point of the curve contained in the map information while the driver does not operate the steering wheel, the control apparatus determines from the front image that there is departure of the vehicle from the lane or possibility of departure of the vehicle from the lane, then the control apparatus may cause the steering assist force to be generated in order to avoid or recover from departure of the vehicle from the lane. Thus, in the determination regarding departure of the vehicle from the lane based on front images, the use of the information about the start point of the curve contained in the map information makes it possible to highly accurately determine the need for a lane departure avoidance or recovery process.
According to a third aspect of the disclosure, there is provided a vehicle travel support method that uses a vehicle travel support system that includes an image pickup apparatus that takes a front image of a view ahead of a vehicle, a lane detection apparatus that detects a lane indicated on a travel path of the vehicle from the front image acquired by the image pickup apparatus, a position detection apparatus that detects a present position of the vehicle, a map information storage apparatus that stores map information, an actuator that generates a steering assist force, and a control apparatus that assists in keeping the vehicle in the lane or avoiding departure of the vehicle from the lane by causing the actuator to generate the steering assist force. The vehicle travel support method includes causing the control apparatus to estimate the travel path of the vehicle based on the present position of the vehicle and the map information, acquire, regarding a curve included in the travel path, a curve radius contained in the map information from the map information storage apparatus, perform a vehicle turning support or a deceleration support prior to entry to the curve, based on a start point of the curve which is detected based on the front image, and perform the vehicle turning support for the curve by using the curve radius contained in the map information, when steering is performed by a driver of the vehicle.
According to a fourth aspect of the disclosure, there is provided a vehicle travel support method that uses a vehicle travel support system that includes an image pickup apparatus that takes a front image of a view ahead of a vehicle, a lane detection apparatus that detects a lane indicated on a travel path of the vehicle from the front image acquired by the image pickup apparatus, a position detection apparatus that detects a present position of the vehicle, a map information storage apparatus that stores map information, an actuator that generates a steering assist force, and a control apparatus that assists in keeping the vehicle in the lane or avoiding departure of the vehicle from the lane by causing the actuator to generate the steering assist force. The vehicle travel support method includes causing the control apparatus to estimate the travel path of the vehicle based on the present position of the vehicle and the map information, acquire, regarding a curve included in the travel path, a curve radius contained in the map information from the map information storage apparatus, and reduce, while performing the vehicle turning support for the curve by using the curve radius contained in the map information, the steering assist force so that the vehicle turning support ends at an end point of the curve which is detected based on the front image.
According to this disclosure, during the vehicle turning support for a curve by using the curve radius contained in the map information, the steering assist force is reduced so that the vehicle turning support will end at the end point of the curve which is detected on the basis of front images. Therefore, it becomes possible to perform a highly accurate vehicle turning support for a curve based on the map information and end the vehicle turning support at an appropriate timing with reference to the end point of the curve which is detected with high accuracy by using front images.
According to the disclosure, it becomes possible to more suitably perform the vehicle travel support when the vehicle turns a curve. It also becomes possible to prevent a sense of strangeness about the steering assist force from being given to the driver of the vehicle.